Starting-rheostat for electric motors



A. H. AND R. A. BUCKLEY.

STARTINGRHEOSTAT FOR ELECTRIC MOTORS.

Patented Feb. 15,1921.

APPLICATION FILED SEPT- 4, I919 I area/011s- Mm UNITED srA'r es-gga'rsur OFFICE.

ARTHUR HERBERT BUCKLEY AND REGINALD ALWYNE BUCKLEY, or :enmamo'ron,

NEW SOUTH WALES, AUSTRALIA.

STARTING-RHEOSTAT FOR ELECTRIC MOTORS.

To all whom it mag concern:

Be it known that we, ARTHUR HERBERT B'UcKLnY and RncINALnALwYNn BnoKLnY, subjects of the King of Great Britain and Ireland, residing at 47 Park road, Paddington, State of New South Vales, Commonwealth of Australia, have invented new and useful Improvements in Starting-Rheostats for Electric Motors, of which the following is a specification.

In motor'starting rheostats of the type most commonly used at present, serious trouble often occu'rsyowing to the contact studs becoming pitted and carbonized. This causes suflicient friction to revent the bandle springing back to the o 7 position, with the result, that when the current is again switched on at the main switch, the motor is still in circuit and a number of the starting resistan'ces'cut out. The effect is to throw the full, or nearly the full, current, on to the motor and thus cause the fuse to blow out or the motor armature to be burnt.

To overcome this disability'we have made certain additions to, and rearranged the parts of the rheostatwhichmake it impossible'to throw the current on to the motor after it has, for anyreason, been cut off, unlessthe operator goes to the rheostat and returns the handle to the off position and then moves it over the contact studs to the runningposition in the usual way.

Instead of makin the line connection direct to the handle, it is madeto a two-way lever arm that is operated by a cam on the inner end of the handle to which latter is electrically connected a stud with which one arm of the two-way lever arm will make contact when operated by the cam handle. v

To illustrate the invention, two figures are shown on the accompanying sheet of drawings V Figure 1 being a front view of the start in rheostat with the cover removed, and

Fig. 2 is a diagrammatic sketch showing the'circuits and the general disposition of the parts when the handle has been moved to the first live contact stud.

1 is the metal box containing the ordinary resistance coils 2 which are connected to the contact studs 3 in the usual way. 4 is the contact lever which works on a pivot ,5 by operating the insulated handle 6. The con tact lever is providedwith a spring'l, for

Specification of Letters mam.

on the;

Patented Feb. 15, 1921.

Application filed September 4,1919 Serial No. 321,641.

the purpose of bringing it back to the oil position (as shown at Fig. 1), and a cam 8 which depresses the cam 9 on the rear end of the two-way lever arm 10. 11 and 12 are stops for limiting the movement of the contact lever 4. 13 is a catch pivoted at 14, and

adapted to engage with the pin 15 when the contact lever is moved over to the full on position. 16 is an insulated handle for op- The double arm lever 10 is pivoted at 21 and i the long arm thereof is provided with a contact piece 22 which makes contact with the contact piece To insure that the extreme surfaces 8 and 9 of the cams 8 and 9 may pass one another when the'contact lever 4 is moved to full on, the contact piece 23 is provided with a short rod24 adapted to slide freely in the contact stud 26, as shown at 25, a helical spring 27 and stop nut 24*. This arrangement while not making the piece 23 a rigid point, insures contactbetween the contact pieces 22 and 23 when'the current is on.

One end of the spring 28, in extension, is connected to a stud 29 on the box 1, while the other end is connected to the end of the short arm of the double arm lever 10. It will, therefore, be seen that should the current be cut ofi', the electromagnet will be come demagnetized, thus releasing the armature 19, and the action of the spring 28 will pull the short arm back from the position shown at Fig. 2 to that shown at Fig. 1, thus breaking the contact between the pieces 22 and 23.

Referring now more particularly to Fig. 2, L is the line terminal, the circuit of which is to the two-way lever arm 10, contact piece 22, contact piece 23, thence to the contact stud 26. which is in electrical connection with the contact lever arm a through the wire 30, thence to the respective contact studs 3 and. resistance coils 2, and back to the armature terminal. F is the field terminal, the circuit of which is from the terminal F through the electromagnet 18 to the first contact stud 3, through the resistance coils, back to the armature terminal. The armature terminal is connected direct to the last of the contact studs 3.

li e claim 1- l. The combination with a rheostat provided with a plurality of resistance coils and a contact stud for each coil, of an arm adapted to be swung into contact with said studs successively and to close an electrical circuit through said coils, magnetic means for maintaining said circuit closed, mechanical means for retaining said arm in contact with the last stud. and means hetween said arm and magnetic means for opening the circuit upon cessation oi. the current while the arm is retained by said mechanical means.

2. The combination with a rheostat provided with a pluralit of resistance coils and a contact stud for each coil, of an arm adapted to he swung into contact with said studs successively, a pivoted lever normally out of contact with said arm, means carried by the arm for swinging said lever on its pivot thereby to close an electrical circuit through said coils when the arm contacts with the first stud, magnetic means for retaining the circuit closed while the arm con tacts with the successive studs, mechanical means for retaining the arm in contact with the last stud, and means carried by said lever for opening the circuit upon cessation of the current.

The combination with a rheostat provided with a plurality of resistance coils and a contact stud for each coil, oi an arm adapted to be swung into contact with said studs successively, a pivoted lever normally out of contact with said arm, cooperating cam surfaces carried by the arm and lever for swinging said lever on its pivot thereby to close an electrical circuit through said coils when the arm contacts with the first stud, an elcctromagnet adapted to be energized by the on rent through said circuit, an armature pivoted on said lever in position to be attracted by said magnet and to retain the circuit closed after said cam surfaces have passed out of contact with each other, mechanical means for holding the arm in contact with the last stud, and a spring for swinging said lever on its pivot upon cessation of the current through said circuit thereby to carry the armature awav from the magnet.

The combination with a rheostat provided with plurality of resistance coils. a contact stud for each coil and a line wire for supplying current to said resistance coils, of an arm adapted to be swung into contact with said studs respectively, said arm being normally out o'l. electrical contact with said wire, a pivoted lever directly connected with said wire, means between said lever and arm for closing the circuit through said arm and coils, cooperating means carricd by said arm and lever for swinging the lever on its pivot thereby to close said circuit, magnetic means for maintaining said circuit closed while the arm passes in contact with successive studs, mechanical means for holding the arm in contact with the last stud, and means for opening said circuit upon cessation of the current while said arm is held by said mechanical means.

In testimony whereof we have signed our names to this specification in the presence at two subscribing witnesses.

ARTHUR HERBERT BUCKLEY REGINALD ALWYNE BUCKLEY. lVitnesses H. Maseru, H. B. CAMPBELL. 

